The present invention relates to antimicrobial organic polymer materials capable of killing microorganisms, fungi, bacteria, viruses or the like in air or liquids.
Infectious diseases found on the medical field are known to often induce serious conditions and thought to be caused by antibiotic-resistant bacteria such as MRSA, VRSA and VRE or fungi, bacteria, viruses or the like. These are so-called nosocomial infections, which are not only contagious but also air-borne. Therefore, it is necessary to sterilize the outside air to be taken in or the inside air in closed spaces such as operating rooms, intensive care units or the like. The same problem occurs in closed spaces such as airplane cabins. A conventional means for sterilizing the air is an HEPA filter, which cannot be always an excellent sterilizing means because it suffers high air pressure losses and viruses pass through it and cannot be eliminated.
An object of the present invention is to solve these problems and to provide a filter material capable of killing microorganisms, fungi, bacteria, viruses or the like in the air or liquids.
It is well known that iodine has high antiseptic activity. For example, aqueous solutions of polyvinyl pyrrolidone carrying triiodide ion (povidone iodine) are widely used as antiseptics or mouth washers. However, povidone iodine shows high water solubility so that filter materials simply impregnated with this substance cannot serve as antimicrobial filters because the absorbed povidone iodine is totally released as soon as a liquid to be treated is passed through such filters. As a result of careful studies to provide a filter material fulfilling the above object by using this highly aseptic iodine, we accomplished the present invention on the basis of the finding that an antimicrobial organic polymer material capable of gradually releasing iodine molecules in triiodide ion into air or an aqueous medium to kill microorganisms can be provided by introducing a functional group capable of carrying triiodide ion (I331 ) into a polymer side chain of an organic polymer material so that triiodide ion is carried on this polymer side chain via the functional group. As used herein, the term xe2x80x9cantimicrobialxe2x80x9d includes all of antimicrobial, antifungal, antibacterial, antiviral, etc.
Accordingly, the present invention relates to an antimicrobial organic polymer material comprising an organic polymer material having a polymer side chain containing a unit derived from an N-alkyl-N-vinylalkylamide on a backbone of a polymer substrate, wherein triiodide ion (I3xe2x88x92) is carried on said organic polymer material. As used herein, the expression xe2x80x9ctriiodide ion is carriedxe2x80x9d means that triiodide ion and I2 form a polyiodine to provide an adduct as counter ion to be carried on the polymer side chain.
N-alkyl-N-vinylalkylamides such as N-vinylpyrrolidone are widely known to bind to iodine as described above. However, no attempt has been so far made to provide an antimicrobial material having triiodide ion carried on said N-alkyl-N-vinylalkylamide group introduced in the form of a polymer side chain into a polymer substrate such as a resin or a nonwoven fabric.
Generally when a functional group is introduced into an organic polymer to confer a specific function, the backbones are crosslinked to each other to compensate for the deterioration of physical strength caused by the introduction of this functional group. Typical examples thereof are ion exchange resins, in which an ion exchange group such as a sulfone or quaternary ammonium group is generally introduced into a polystyrene backbone obtained by polymerizing a styrene monomer. However, these ion exchange groups are hydrophilic groups that are bulky by the surrounding several coordinated water molecules so that the resins are insufficient in physical strength and dissolve even in water. In order to solve this problem with ion exchange resins, polystyrene backbones are crosslinked to each other with a crosslinker such as divinylbenzene. This enhances physical strength of the resins, which no more dissolve in water, but the formation of a crosslinked structure impairs absorption/desorption functions such as absorption speed or diffusion speed. This problem also occurs when an N-alkyl-N-vinylalkylamide is introduced into a backbone of an organic polymer substrate. That is, polymer materials cannot hold physical strength when an N-alkyl-N-vinylalkylamide group is directly introduced onto a polymer backbone, but their adsorption function is deteriorated if polymer backbones are crosslinked to each other for holding physical strength.
According to the present invention it was found that an N-alkyl-N-vinylalkylamide group can be introduced into an organic polymer substrate while holding the physical strength of the polymer backbones by attaching a side chain in the form of a polymer chain containing a unit derived from the N-alkyl-N-vinylalkylamide onto a polymer backbone of the organic polymer substrate. The present invention will now be further explained in detail.